Actions that fail to perform as expected throw exceptions. These exceptions can either be rescued for the public view (with a nice user-friendly explanation) or for the developers view (with tons of debugging information). The developers view is already implemented by the Action Controller, but the public view should be tailored to your specific application.
The default behavior for public exceptions is to render a static html file with the name of the error code thrown. If no such file exists, an empty response is sent with the correct status code.
You can override what constitutes a local request by overriding the local_request? method in your own controller. Custom rescue behavior is achieved by overriding the rescue_action_in_public and rescue_action_locally methods.
True if the request came from localhost, 127.0.0.1. Override this method if you wish to redefine the meaning of a local request to include remote IP addresses or other criteria.
# File lib/action_controller/rescue.rb, line 124 def local_request? #:doc: LOCALHOST.any?{ |local_ip| request.remote_addr =~ local_ip && request.remote_ip =~ local_ip } end
Overwrite to implement custom logging of errors. By default logs as fatal.
# File lib/action_controller/rescue.rb, line 79 def log_error(exception) #:doc: ActiveSupport::Deprecation.silence do if ActionView::TemplateError === exception logger.fatal(exception.to_s) else logger.fatal( "\n#{exception.class} (#{exception.message}):\n " + clean_backtrace(exception).join("\n ") + "\n\n" ) end end end
Attempts to render a static error page based on the status_code thrown, or just return headers if no such file exists. At first, it will try to render a localized static page. For example, if a 500 error is being handled Rails and locale is :da, it will first attempt to render the file at public/500.da.html then attempt to render public/500.html. If none of them exist, the body of the response will be left empty.
# File lib/action_controller/rescue.rb, line 107 def render_optional_error_file(status_code) status = interpret_status(status_code) locale_path = "#{Rails.public_path}/#{status[0,3]}.#{I18n.locale}.html" if I18n.locale path = "#{Rails.public_path}/#{status[0,3]}.html" if locale_path && File.exist?(locale_path) render :file => locale_path, :status => status, :content_type => Mime::HTML elsif File.exist?(path) render :file => path, :status => status, :content_type => Mime::HTML else head status end end
Exception handler called when the performance of an action raises an exception.
# File lib/action_controller/rescue.rb, line 72 def rescue_action(exception) rescue_with_handler(exception) || rescue_action_without_handler(exception) end
Overwrite to implement public exception handling (for requests answering false to local_request?). By default will call render_optional_error_file. Override this method to provide more user friendly error messages.
# File lib/action_controller/rescue.rb, line 96 def rescue_action_in_public(exception) #:doc: render_optional_error_file response_code_for_rescue(exception) end
Render detailed diagnostics for unhandled exceptions rescued from a controller action.
# File lib/action_controller/rescue.rb, line 130 def rescue_action_locally(exception) @template.instance_variable_set("@exception", exception) @template.instance_variable_set("@rescues_path", RESCUES_TEMPLATE_PATH) @template.instance_variable_set("@contents", @template.render(:file => template_path_for_local_rescue(exception))) response.content_type = Mime::HTML render_for_file(rescues_path("layout"), response_code_for_rescue(exception)) end
# File lib/action_controller/rescue.rb, line 141 def rescue_action_without_handler(exception) log_error(exception) if logger erase_results if performed? # Let the exception alter the response if it wants. # For example, MethodNotAllowed sets the Allow header. if exception.respond_to?(:handle_response!) exception.handle_response!(response) end if consider_all_requests_local || local_request? rescue_action_locally(exception) else rescue_action_in_public(exception) end end
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